1. Field of the Invention
The present invention relates to a constant operating speed holding system for a motorcycle and, more particularly, to a constant operating speed holding system for a motorcycle, capable of inhibiting constant operating speed holding operation while the motorcycle is not moving.
2. Description of Background Art
A constant operating speed holding system capable of holding the operating speed constant in response to a constant operating speed hold command. This system is sometimes referred to as an autocruising system which has been developed to mitigate the fatigue of a rider driving a motorcycle and to reduce fuel consumption by suppressing variations in the operating speed.
Accurate detection of the operating speed is essential to stabilize the operating speed at a set operating speed. An operating speed calculating method disclosed in Japanese Patent Publication (Kokoku) No. Sho 49-44830 detects the rotating speed of a magnet rotor attached to one end of the speedometer cable by a magnetic detecting device, such as a reed switch or a Hall device, and calculates the operating speed on the basis of a pulse signal provided by the magnetic detecting device.
In determining the operating speed of the motorcycle on the basis of the rotating speed of the wheel of the motorcycle detected by measuring the revolving speed of the speedometer cable, a detected operating speed in some cases includes an error due to the vibration of the speedometer cable when the motorcycle is caused to vibrate by irregularities in the road surface. Therefore, a constant operating speed holding system employing this known operating speed calculating method repeats, although at rare intervals, useless acceleration and deceleration.
A recently proposed operating speed detecting method developed to detect the operating speed without employing the speedometer cable detects the engine speed and the speed of the transmission, i.e., transmission gear ratio, and calculates the operating speed on the basis of the engine speed and the speed of the transmission.